The present invention relates to an apparatus for calculating a geometrical view factor in performing a calculation about radiant heat.
The present invention relates to an apparatus for calculating the geometrical view factor of a rectangular surface required in performing a calculation quickly and accurately about radiation heat in a three-dimensional region.
The present invention relates to an apparatus for finding a geometrical view factor between a cylindrical surface and a rectangular surface in performing a calculation about radiant heat.
In recent years, radiant air conditioners, for example, a floor heating apparatus and a panel cooling and heating of a ceiling has been developed. In order to develop this kind of floor heating apparatus, it is necessary to know the magnitude of radiant heat applied to the wall of a room in which the floor heating apparatus is installed. In order to calculate the radiant heat, it is necessary to find a geometrical view factor which depends on the angular or positional relationship between the floor heating apparatus and an object, for example, the wall of the room. As a method for finding the geometrical view factor, energy lines are emitted from a point of the floor heating apparatus to a wall to be radiantly heated and the number of energy lines which have reached the wall are counted. The conventional apparatus for calculating the geometrical view factor is constructed as shown in FIG. 16. The operation of the apparatus is described below. A hemispherical surface is assumed around the point of the floor heating apparatus. Zenithal angle calculating means 11 generates random numbers in the zenithal angle direction of the spherical surface to find a zenithal angle of the spherical surface. Horizontal angle calculating means 13 generates random numbers in the horizontal angle direction of the spherical surface to find a horizontal angle of the spherical surface. Arrival deciding means 15 decides whether or not an energy line having the decided zenithal angle and horizontal angle reaches a surface of an object. Based on the number of emitted energy lines, arrival intensity adding means 16 calculates the intensities of energy lines at the surface which they have reached. Geometrical view factor calculating means 17 finds the ratio of the intensities of all emitted energy lines to find a geometrical view factor. Refer to a magazine entitled as "Thermal Radiation View Factor Calculation Using Monte Carlo Method, Comparison of Accuracy and Computer Time with Area Integration Method" written by Takeshi IKUSHIMA and et al. and published by Japan Atomic Society, 1988, Vol. 30, No. 6, page 64-page 70.
FIG. 17 is an image view showing a method for generating energy lines by utilizing random numbers so as to calculate the number of energy lines which have reached each surface.
However, according to the above-described conventional method, since random numbers are utilized, energy lines emitted from a certain point of an energy source are not necessarily emitted isotropically toward a hemisphere, which means that the number of energy lines cannot be accurately calculated when a small number of energy liens are emitted from the emission point. If many energy lines are emitted therefrom, it takes long to perform a calculation.
According to the conventional method, a geographical view factor between rectangular surfaces is found as follows: The rectangular surface of a three-dimensional region are divided as shown in FIG. 18; energy lines each having an intensity are emitted from a divided rectangular surface of the floor of the region energy source in various directions; the intensity of each energy line which has reached an object rectangular surface of a solid wall of the region is calculated; and the ratio of the intensities of energy lines which have reached the object rectangular surface of the solid wall to the intensity obtained by adding the intensities of all energy lines emitted from the divided rectangular surface is found and then the geometrical view factor between the divided rectangular surface of the floor and the object rectangular surface of the solid wall is founded (Papers of lectures given at meeting of Air Conditioning Sanitary Engineering Society, 1990, page 1161 through 1164). Supposing that the emitted energy lines reach the object rectangular surface of the solid wall directly, arrival positions of energy lines are calculated.
However, according to the above conventional method, in a space such as a room accommodating a furniture or a furnishing as shown in FIG. 19, an accurate geographical view factor cannot be obtained because it is assumed that the emitted energy lines directly reach the surface of the solid wall and then the existence of the furniture is not considered. In analyzing hot air flow in the room, the space is divided with fine mesh as shown in FIG. 9. In order to quickly trace an energy line in the space which is regarded as not absorbing radiation heat, it is necessary to regenerate meshes by an element which constitutes a solid body which absorbs radiant heat as shown in FIG. 10.
When the transmission of radiant heat from air conditioning equipments such as a floor heating equipment, a panel cooling and heating of a ceiling, or the like is calculated, it is necessary to find a geographical view factor which is determined according to an angle and a position. Specially, it is necessary to find a geographical view factor between a human body and a rectangular surface in order to calculate the transmission of radiant heat between the human body and a radiant wall. In such calculations, a model is considered as the human body in order to perform the calculations. Conventionally, the human body is regarded as a microelement to find the geographical view factor between the micro-cylinder and the rectangular surface as shown in FIG. 20. This method is described in a magazine of "Ann. Physiological Anthrop." published in 1988, in 7(3), on pages 143 through 150. In order to find the geographical view factor, an area integration equation is used by finely dividing the cylindrical surface and the rectangular surface.
However, according to the conventional art, it takes a long period of time for calculations to be performed because cylindrical and rectangular surfaces must be finely divided. In addition, it is necessary to limit an integration range if another rectangular surface is interposed between the cylindrical surface and the rectangular surface. Thus, accurate calculations cannot be performed. Further, in performing calculation, attention is not paid to the actual dimensions of the human body. Therefore, the influence of radiant heat from the rectangular surface to the human body is not correctly calculated.